In semiconductor manufacture and in related processing schemes which are dependent upon smooth, defectfree surfaces (i.e., surfaces free from scratches, divots, voids, and the like), it becomes necessary to have methods for repairing (or healing) defects which may occur in the surface. In the manufacture of semiconductors, for instance, there are steps involving chemical and mechanical polishing or planarizing of the wafer surface. These polishing or planarizing steps often cause scratches and other defects on the wafer surface. With the advent of microminiaturization of electronic devices, the need for damage-free and smooth semiconductor wafer surfaces has become increasingly important. Accordingly, there is a need for a method of repairing these defects.
Currently, there are relatively few methods for repairing polishing scratches, each of which has its related problems. The most commonly used method for eliminating a scratch is to polish the layer down (i.e., reduce the thickness) until the scratch is no longer present. This method is obviously ineffective, however, if the scratches are too deep. Another commonly used method entails increasing the environmental temperature around the surface layer whereby the layer melts and reflows into the defects. In other words, the layer fills its own scratches. Because this process requires elevated temperatures, however, it can only be used with insulating materials having a low melting point. If the temperature gets too high, doped regions of the workpiece will diffuse causing a degradation of electrical performance. This thermal processing limitation is referred to as thermal budget.
Therefore, there is a need for a surface defect repair method which does not impact the thermal budget of the workpiece, and which is effective in removing even deep scratches.